The present invention is directed toward a fitting gear and more particularly toward a fitting gear in the form of an electromagnetic U-bar which is intended to assist in the alignment of two metal plates so that the edges thereof can be welded together.
It is frequently desirable to weld plates together along their edges. This is done, for example, when constructing the outer shell or covering the outer surface of a large tank or building or other structure. These steel plates may have, for example, a thickness between 3/16 and 1/4 of an inch although the invention described herein may be applicable to plates that are thinner or thicker than these.
The steel plates may be welded together utilizing either a lap welding technique or a butt welding technique. In lap welding, the edges of the steel plates overlap each other by a small amount such as an inch or so and the outermost extreme edge of the upper plate is welded to the upper surface of the underlying plate adjacent its edge. When utilizing a butt welding technique, the extreme edges of the two plates are place adjacent to each other with the plates lying in the same plane and the extreme edges of each of the plates are then welded to each other.
When employing either the lap welding or butt welding technique, it is necessary for the edges of the two plates to be in alignment with each other in order to effectuate a good weld from both a mechanical and aesthetic standpoint. That is, if the edges of the plates are not in direct contact with each, they cannot be uniformly welded along their length.
Two plates frequently do not perfectly align with each other due to imperfections in the plates. That is, the edge of one plate may be slightly bent along its length thereof with respect to the other or may have minor undulations or waves. It is, therefore, necessary to flatten the two edges of the adjacent plates with respect to each other so that they are in proper alignment for welding.
FIGS. 1 and 3 of the enclosed drawings illustrate one method currently used to facilitate the alignment of the edges of two metal plates for welding. The prior art fitting gear 10 shown in FIGS. 1 and 3 is comprised essentially of a plurality of inverted U-shaped bolts 12 which cooperate with a like number of tapered bull pins 14 or the like. Each of the U-bolts 12 is welded to the upper surface 16 of one of the plates 18 adjacent edge 20 thereof. These are welded in a conventional manner utilizing any known technique and the weld lines are clearly shown at 22 in FIGS. 1 and 3. The leading edge 24 of the second plate 26 is then placed over the edge 16 of the first plate 18. Pins 14 are then forced through the U-bolts so as to force the edges of the two plates together. Since the pins 14 are elongated and tapered, the edges of the two plates are essentially cammed together as the pins engage the upper portion of the bolts 12 and the upper surface of the forward edge 24 of the plate 26.
The number of U-bolts 12 that may be required depends on the thickness of the plates 18 and 26 and the amount of curvature or wave that prevents the plates from coming into contact with each other. It may sometimes be necessary to use a large number of U-bolts 12 spaced only a few inches from each other or it may be necessary to utilize only a few such bolts placed several feet apart from each other. In any event, once the bolts 12 and pins 14 are in place and the plates are in contact with each other, the edges of the plates are welded together, again, utilizing any known welding technique.
After the plates have been welded together, the U-bolts 12 must then be removed. This is normally done by simply breaking the U-bolts off or dewelding them by again providing the necessary heat or electrical energy in order to destroy the welds. In either event, however, the previous weld spots must either be removed or present cosmetically unappealing appearances. Either choice is clearly non-desirable.
Applicant is also aware of the fact that electromagnetic energy has been utilized to assist in the alignment of metal parts so that they can be joined together. Complex arrangements for accomplishing the same are shown, for example, in U.S. Pat. Nos. 3,582,609; 3,618,844; 3,701,881 and 5,203,427. To Applicant's knowledge, no one has considered utilizing electromagnetic forces in the manner proposed in the present application.